The invention relates generally to robotics and is concerned in particular with an improved apparatus for manipulating workpieces and the like.
There are a wide variety of manufacturing operations which involve the handling and processing of individual workpieces. The workpiece may be carried sequentially through a plurality of workstations where various tasks may be performed such as stamping, deburring, dipping, etc.
If the workpiece is completely released at a workstation, after being retrieved the workpiece usually must be reoriented to a known attitude and position before further processing can take place, this takes time. In such manufacturing operations, it is desirable to maintain hold of the workpiece as it is processed, both to control the location of the workpiece as it is introduced into a workstation and to save the time needed to regrasp the finished piece.
The known automated workpiece handling systems are generally used where there is no need to control the location of the workpiece by the manipulator or where the finished piece need not be regrasped after processing. One of the reasons for this is that the manipulators in these systems are rigid and massive. They are not designed to be compliant and to accomodate the shock force that may be produced at a workstation for example by a press. Further, they cannot release and regrasp the workpiece with sufficient speed to be particularly advantageous. There are manufacturing operations where it would be desirable both to rigidly grasp the workpiece and move it to a workstation, and at the workstation, to relax the grip on the workpiece such that during a stamping operation or the like, the workpiece could move while the gripper maintained its grasp on the workpiece.
Our invention accomplishes the foregoing by providing a linkage device which is advantageously secured at one end to a robot arm and secured at the other end to a gripper, which gripper holds a workpiece. The linkage device, upon command, provides for relative angular movement between its ends and therefore between the workpiece and the robot arm. When the workpiece is subjected to shock the linkage absorbs the shock.
Our invention in a preferred embodiment provides a linkage device having a first link secured to a first object, such as a robot arm, and a second link secured to a second object, such as a gripper which holds a workpiece. The first and second links are disposed in a housing and adapted for relative angular motion one to the other. The device further includes locking pistons to rigidly secure the links within the housing; and alignment rings to reorient the links. The device functions in at least one of three modes; a locking mode to provide a rigid linkage between the objects; an air bearing mode which provides a flexible linkage between the objects; and an alignment mode to provide a standard resettable linkage between the objects.